Exercise mat



FIG. 1 is a perspective view of an exercise mat showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The parts of the exercise mat drawn in broken line form no part of the claimed design. 

The ornamental design for an exercise mat, as shown and described. 